The present invention generally relates to superconducting devices. More specifically, the present invention relates to Josephson junctions for improved qubits.
Several physical objects have been suggested as potential implementations of qubits. However, solid-state circuits, and superconducting circuits in particular, are of great interest as they offer scalability, which allows circuits to be formed with a larger number of interacting qubits. Superconducting qubits are typically based on Josephson junctions. A Josephson junction is two superconductors coupled by, for example, a thin insulating barrier. A Josephson junction can be fabricated by means of an insulating tunnel barrier, such as Al2O3, between superconducting electrodes. For such Josephson junctions, the maximum allowed supercurrent is the critical current Ic. Superconducting tunnel junctions (also referred to as Josephson junctions) used in superconducting quantum chips exhibit a Josephson inductance, which is equivalent to a conventional inductor within the circuit except for the ability to provide superconducting current.